Some enterprise storage (backup) systems may be comprised of many separate physical storage volumes, with each physical storage volume controlled by external control logic and local disk access modules, and with the separate physical storage volumes represented to a host system as one or more logical volumes. These control logic modules and disk access modules are typically separate hardware elements in the system, and each may also include software or firmware. When a host system transmits an access request to the storage system, unlike consumer storage systems which only include a single connection to the storage, in these enterprise storage systems, which are sometimes called “active-active” arrays, the request may be received at any one of the control logic modules in the system. Thus, in such a system, the data may be located on a separate physical storage volume. In such a case, after the control logic device sends the access request to the disk access module, the disk access module may have to communicate with a remote disk access module that is physically connected to the desired physical storage volume. Such a remote access is slow compared to accessing the physical volume directly connected to the disk access module.
One existing solution to such a problem is that the control logic module may attempt to access the disk access modules of the storage volume in a round robin fashion. Thus, if a system has four disk access modules, then a control logic module may send requests first to the first module, then the second, the third, and the fourth, before returning to the first. In this fashion, for certain access requests, the request is sent to the disk access module that has the requested data on a locally connected physical storage volume. This improves the speed of the access. However, while this may improve performance over accessing one of the disk access modules, it is still random and does not always access the best disk access module.
Thus, it would be desirable to have a better method of accessing the data on the physical storage volumes of these enterprise storage systems.